The present invention broadly relates to a new and improved construction of an apparatus for venting liquid-filled systems.
In its more specific aspects the present invention . relates to a new and improved construction of a venting apparatus for liquid-filled systems and comprises a lower or bottom member with an internal bore provided for an upwardly and downwardly displaceable, spring-loaded plunger. A venting channel communicates with at least one air exit opening and contains a central bore which may accommodate operating means for operating the plunger. The top member carries a protective cap.
An automatic venting apparatus of this type as described, for example, in German Patent No. 1,935,899, comprises an air compression chamber. A stepped plunger or piston controls or displaces the compressed air through an outlet opening, and the air exits or vents through small escape apertures in a protective cap. If there is no air present in the system, the compression chamber is filled with liquid instead of air. Upon a pressure increase, such liquid is forced by the plunger or piston through the small escape apertures into the ambient atmosphere or surroundings. This may result in clogging the small escape apertures due to dust depositions therein. Furthermore, the proper function of this automatic venting apparatus is dependent upon the presence of a number of seals at the plunger or piston and which seals are reciprocated conjointly with the plunger or piston in associated guide means. The seals are damaged by small foreign bodies or particles, and the plunger or piston is jammed which can result in non-operability of the venting apparatus.
In a further venting valve comprising a plunger or piston, the air outlet connector at the top member is constructed and arranged without protection, such that dust and foreign particles or bodies unobstructedly and directly may enter the valve and, due to deposition or corrosion, adhere at the plunger or piston and impair its function.
There exist still other known automatic venting apparatuses in which the plunger or pistons are provided with helical turns or grooves and otherwise are tightly guided in bores. Also in these apparatuses the function is impaired whenever small foreign particles or bodies are deposited in the turns or grooves and cause jamming of the plunger or piston.